I've been restoring a Firestone 4-A-124, and there's a foul odor (not sound!) coming from the speaker. There's no evidence of rodent damage in the chassis, so I don't know what's gotten into the cone that created the smell. Does anyone out there know what might cause this, and...is it safe to spray it Febreeze or something to kill the smell????

Thanks for your help!
Jeff S.